: Mammalian chemical signals emitted by one individual which act to alter reproductive physiology in a cospecific recipient (e.g., acceleration of puberty, estrous cycle regulation and release from estrous suppression) are termed primer pheromones. Hormonal response to cospecific chemosignals often act by increasing luteinizing hormone (L.H). Primer-like pheromone effects in humans include an alteration of the length and timing of the menstrual cycle using serial applications of male or female axillary secretion extracts upon females. Axillary secretions appear to be the "best candidate" human odor source with chemical communicator properties. The investigators have initiated a program to determine the chemical character of axillary secretions and develop a reliable method to assess chemical constituents for pheromone-like activity. This proposal presents data which suggest that application of a male axillary extract to the nasal area of female volunteers, affects the pulse pattern of L.H. The investigators will employ this bioassay to guide an analytical study into the active axillary extract constituents. In addition, this study will help elucidate neuroendocrine mechanisms involved in olfactory modulation of the menstrual cycle. Understanding this mechanism may provide insight into other menstrual disorders which are associated with subtle alterations in LH pulsing and thought to be related to environmental influences such as hypothalamic amenorrhea and infertility due to an inadequate luteal phase. In parallel, the investigators will continue studies of axillar odor chemistry. The investigators plan to determine the structure of ASOB1 and examine the 45 kDa protein found in saliva and other body fluids to determine: (a) its structural similarity to apocrine secretion ASOB1, (b) whether it has 3M2H bound to it; and (c) whether odors carried by it and apocrine apoD (ASOB2) after the human menstrual cycle.